Overexpression of the potato StEPF2 gene confers enhanced drought tolerance in Arabidopsis

Yanli Wang,Tian Xie,Chunli Zhang,Juanjuan Li,Zhi Wang,Hongbing Li,Xiping Liu,Li-Na Yin,Shi-Wen Wang,Sui-Qi Zhang,Xiping Deng,Qingbo Ke 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.4

Epidermal patterning factor 2 (EPF2) is a negative regulator of stomatal development, and is essential for plant growth, development, and environmental stress responses. However, the role of EPF2 in potato (Solanum tuberosum) has not been investigated to date. Here, we cloned and characterized the potato EPF2-like gene (StEPF2). StEPF2 is predominantly intercellular space localized and its transcripts were rhythmically expressed, and showed the highest expression in apical unexpanded leaves. Expression of StEPF2 was markedly down-regulated in response to abscisic acid and sodium chloride treatments; however, upon the application of polyethylene glycol, the expression of StEPF2 peaked at 4 h and then decreased gradually. Overexpression of StEPF2 in Arabidopsis (OE) substantially reduced stomatal density and photosynthetic rate, but had little effects on plant growth. Under drought stress, OE lines maintained higher photosynthetic rates, photosystem II efficiency, and instantaneous water use efficiency than wild-type (WT) plants. Moreover, OE lines showed less water loss and hydrogen peroxide accumulation in detached leaves compared with WT plants. Thus, our results suggest that StEPF2 acts as a negative regulator of stomatal development in potato, indicating that the role of EPF2 is conserved across plant species. Overall, StEPF2 represents an important target for the development of drought-tolerant potato cultivars via genetic engineering.

Stress-induced expression of the sweetpotato gene <i>IbLEA14</i> in poplar confers enhanced tolerance to multiple abiotic stresses

Ke, Qingbo,Park, Sung-Chul,Ji, Chang Yoon,Kim, Ho Soo,Wang, Zhi,Wang, Shiwen,Li, Hongbing,Xu, Bingcheng,Deng, Xiping,Kwak, Sang-Soo Elsevier 2018 Environmental and experimental botany Vol.156 No.-

<P><B>Abstract</B></P> <P>Late embryogenesis abundant (LEA) proteins are small, highly hydrophilic proteins that act as protectors of macromolecules and increase abiotic stress tolerance in plants. We previously reported that overexpressing sweetpotato <I>IbLEA14</I> under the control of the <I>CaMV 35S</I> promoter increased osmotic and salt stress tolerance in transgenic sweetpotato calli. In this study, we generated transgenic poplar plants (<I>Populus alba × P. glandulosa</I>) expressing <I>IbLEA14</I> under the control of the oxidative stress-inducible <I>SWPA2</I> promoter (referred to as SL plants). Among the 15 SL plants obtained, three lines (SL2, SL7, and SL12) were established based on <I>IbLEA14</I> transcript levels, tolerance to salt stress and Southern blot analysis. The SL plants exhibited less damage in response to methyl viologen-mediated oxidative stress than non-transgenic (NT) plants. SL plants also showed enhanced tolerance to drought, salt, and heat stress, which was associated with higher photosystem II efficiency and lower malondialdehyde levels compared with NT plants. Furthermore, SL plants had higher levels of monolignol biosynthesis-related gene transcripts under drought stress compared with NT plants. Finally, SL plants exhibited increased tolerance to heat stress, which is associated with the high thermostability of IbLEA14 protein. SL plants might be useful for reforestation on global marginal lands, including desertification and reclaimed areas.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>IbLEA14</I> gene was transformed into poplar plants. </LI> <LI> Transgenic poplars exhibit increased tolerance to MV-mediated oxidative, drought, salt and heat stress. </LI> <LI> Overproduction of IbLEA14 affects lignification and thermostability of transgenic poplars. </LI> </UL> </P>

Changes in plant anthocyanin levels in response to abiotic stresses: a meta-analysis

Yan Wenjie,Li Juanjuan,Lin Xinyue,Wang Lina,Yang Xiaoxiao,Xia Xiangyu,Zhang Yuxin,Yang Shaoyu,Li Hongbing,Deng Xiping,Ke Qingbo 한국식물생명공학회 2022 Plant biotechnology reports Vol.16 No.5

Anthocyanins are small molecule antioxidants that play important roles in plant response and resistance to abiotic stresses. Their levels increase when plants are exposed to abiotic stress. However, the general response patterns and magnitude of anthocyanin increase, and how they confer resistance to abiotic stresses, are difficult to evaluate because of the influence of experimental variables. In this study, changes in plant anthocyanin content under different abiotic stresses and the effect of anthocyanin overproduction on various physiological indicators were investigated through meta-analysis derived from 1039 datasets of 102 studies. Results showed that among the different stress types, heavy metals, especially copper (Cu) and mercury (Hg), induced the most significant synthesis of anthocyanins. Among the different types of drought treatments, mannitol caused anthocyanin content in plants to increase by 2.4-fold, which was more significant than that of polyethylene glycol and natural drought. Furthermore, UV stress led plant anthocyanins to increase 1.3-fold in C4 plants, which was higher than that in C3 plants. In addition, anthocyanins increased the most when the applied stresses were low and moderate, and of short duration. Moreover, plants overexpressing genes encoding MYB transcription factors increased anthocyanin content by 5.8-fold and significantly improved plant stress tolerance. Among the 21 physiological indicators, glutathione and proline levels increased the most in transgenic plants overproducing anthocyanins when exposed to abiotic stress. Taken together, this meta-analysis indicates that anthocyanins enhance stress tolerance by improving the antioxidant, metal-chelating, and osmoregulatory abilities of the plant. The results presented here can help guide future applications of anthocyanins as plant growth regulators in dryland agriculture and breeding for plant stress tolerance.

Meta-analysis of the effect of melatonin application on abiotic stress tolerance in plants

Yang Xiaoxiao,Ren Jianhong,Li Juanjuan,Lin Xinyue,Xia Xiangyu,Yan Wenjie,Zhang Yuxin,Deng Xiping,Ke Qingbo 한국식물생명공학회 2023 Plant biotechnology reports Vol.17 No.1

Melatonin is a hormone-like substance that promotes plant growth and development and alleviates stress levels. Although the physiological roles of melatonin and the underlying mechanisms have been qualitatively reviewed in plants, we do not fully understand when and how to apply melatonin to maximize its benefits. Here, we performed a meta-analysis to quantitatively evaluate the effect of melatonin on abiotic stress tolerance in plants and to determine the number of parameters modulated by melatonin. Melatonin significantly alleviated the growth inhibition induced by drought stress compared with other abiotic stresses, including salt, cold, heat, nitrogen deficit, and heavy metal toxicity, mainly owing to higher photosynthesis efficiency and antioxidant enzyme activity. Furthermore, melatonin modulated plant growth in a concentration-dependent manner and was more effective when applied to plants under moderate drought stress at an early stage via root irrigation. In addition, the impact of melatonin was greater in monocots than in dicots. Moreover, endogenous melatonin levels could be significantly increased via transgenic strategies. Among melatonin biosynthesis-related gene members, ASMT has tended to have the most influence on melatonin content in plants. In light of the rapidly developing genome editing technology, quantitatively increasing endogenous melatonin level in plant would be quite useful for moderating climatic conditions and combating desertification. Taken together, our results provide guidelines for melatonin application in crops plants for improving productivity under ongoing climate change.

Suppression of the <i>β-carotene hydroxylase</i> gene increases β-carotene content and tolerance to abiotic stress in transgenic sweetpotato plants

Kang, Le,Ji, Chang Yoon,Kim, Sun Ha,Ke, Qingbo,Park, Sung-Chul,Kim, Ho Soo,Lee, Hyeong-Un,Lee, Joon Seol,Park, Woo Sung,Ahn, Mi-Jeong,Lee, Haeng-Soon,Deng, Xiping,Kwak, Sang-Soo Elsevier 2017 Vol. No.

<P><B>Abstract</B></P> <P>β-carotene, a carotenoid that plays a key photo-protective role in plants is converted into zeaxanthin by β-carotene hydroxylase (CHY-β). Previous work showed that down-regulation of <I>IbCHY-β</I> by RNA interference (RNAi) results in higher levels of β-carotene and total carotenoids, as well as salt stress tolerance, in cultured transgenic sweetpotato cells. In this study, we introduced the RNAi-<I>IbCHY-β</I> construct into a white-fleshed sweetpotato cultivar (cv. Yulmi) by <I>Agrobacterium</I>-mediated transformation. Among the 13 resultant transgenic sweetpotato plants (referred to as RC plants), three lines were selected for further characterization on the basis of <I>IbCHY-β</I> transcript levels. The RC plants had orange flesh, total carotenoid and β-carotene contents in storage roots were 2-fold and 16-fold higher, respectively, than those of non-transgenic (NT) plants. Unlike storage roots, total carotenoid and β-carotene levels in the leaves of RC plants were slightly increased compared to NT plants. The leaves of RC plants also exhibited tolerance to methyl viologen (MV)-mediated oxidative stress, which was associated with higher 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical-scavenging activity. In addition, RC plants maintained higher levels of chlorophyll and higher photosystem II efficiency than NT plants after 250 mM NaCl stress. Yield of storage roots did not differ significantly between RC and NT plants. These observations suggest that RC plants might be useful as a nutritious and environmental stress-tolerant crop on marginal lands around the world.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Transgenic sweet potato plants were generated by RNAi silencing of the <I>IbCHY-β</I> gene. </LI> <LI> Transgenic sweet potato plants had increased β-carotene and total carotenoid content. </LI> <LI> Transgenic sweet potato plants exhibited strong antioxidant capacity and salt stress tolerance. </LI> </UL> </P>

Down‐regulation of <i>GIGANTEA</i> ‐ <i>like</i> genes increases plant growth and salt stress tolerance in poplar

Ke, Qingbo,Kim, Ho Soo,Wang, Zhi,Ji, Chang Yoon,Jeong, Jae Cheol,Lee, Haeng‐,Soon,Choi, Young‐,Im,Xu, Bingcheng,Deng, Xiping,Yun, Dae‐,Jin,Kwak, Sang‐,Soo John Wiley and Sons Inc. 2017 Plant biotechnology journal Vol.15 No.3

<P><B>Summary</B></P><P>The flowering time regulator GIGANTEA (GI) connects networks involved in developmental stage transitions and environmental stress responses in <I>Arabidopsis</I>. However, little is known about the role of GI in growth, development and responses to environmental challenges in the perennial plant poplar. Here, we identified and functionally characterized three <I>GI‐like</I> genes (<I>PagGIa</I>,<I> PagGIb</I> and <I>PagGIc)</I> from poplar (<I>Populus alba × Populus glandulosa</I>). <I>PagGIs</I> are predominantly nuclear localized and their transcripts are rhythmically expressed, with a peak around zeitgeber time 12 under long‐day conditions. Overexpressing <I>PagGIs</I> in wild‐type (WT) <I>Arabidopsis</I> induced early flowering and salt sensitivity, while overexpressing <I>PagGIs</I> in the <I>gi‐2</I> mutant completely or partially rescued its delayed flowering and enhanced salt tolerance phenotypes. Furthermore, the PagGIs‐PagSOS2 complexes inhibited PagSOS2‐regulated phosphorylation of PagSOS1 in the absence of stress, whereas these inhibitions were eliminated due to the degradation of PagGIs under salt stress. Down‐regulation of <I>PagGIs</I> by RNA interference led to vigorous growth, higher biomass and enhanced salt stress tolerance in transgenic poplar plants. Taken together, these results indicate that several functions of <I>Arabidopsis GI</I> are conserved in its poplar orthologues, and they lay the foundation for developing new approaches to producing salt‐tolerant trees for sustainable development on marginal lands worldwide.</P>