Sivalingam P N, Mahajan Mahesh M, Satheesh Viswanathan, Chauhan Sarita, Changal Harish, Gurjar Karun, Singh Dhurendra, Bhan Chander, Sivalingam Anandhan, Marathe Ashish, Ram Chet, Dokka Narasimham, More T A, Padaria J C, Bhat K V, Mohapatra T
ICAR-Central Institute for Arid Horticulture, NH-15 Sri Ganganagar Road, Beechwal, Bikaner, Rajasthan 334 006, India.
ICAR-National Institute of Biotic Stress Management, Baronda, Raipur, Chhattisgarh 493225, India.
Tree Physiol. 2021 Nov 8;41(11):2063-2081. doi: 10.1093/treephys/tpab058.
Tree species in the arid and semi-arid regions use various strategies to combat drought stress. Ziziphus nummularia (Burm. f.) Wight et Arn., native to the Thar Desert in India, is highly drought-tolerant. To identify the most drought-tolerant ecotype of Z. nummularia, one ecotype each from semi-arid (Godhra, annual rainfall >750 mm), arid (Bikaner, 250-350 mm) and hyper-arid (Jaisalmer, <150 mm) regions was selected along with two other Ziziphus species, Ziziphus mauritiana Lamk. and Ziziphus rotundifolia Lamk., and screened for parameters contributing to drought tolerance. Among these, Z. nummularia (Jaisalmer) (CIAHZN-J) was the most drought - tolerant. The tolerance nature of CIAHZN-J was associated with increased membrane stability, root length and number, length of hairs and thorns, root dry/fresh weight ratio, seed germination (at -0.5 MPa), proline content (31-fold), catalase and sugar content (two- to three-fold). Apart from these characteristics, it also exhibited the longest duration to reach highest cumulative drought stress rating, maintained higher relative water content for a longer period of time with reduced leaf size, leaf rolling and falling of older leaves, and displayed sustained shoot growth during drought stress. To determine drought tolerance in Ziziphus, we developed a morphological symptom-based screening technique in this study. Additionally, transcriptome profiling of CIAHZN-J in response to drought revealed the up-regulation of genes involved in sugar metabolism and transport, abscisic acid biosynthesis, osmoregulation, reactive oxygen species homeostasis and maintaining water potential. Expression profiles and semi-quantitative reverse transcription PCR results further correlated with the physiological and biochemical mechanisms. In conclusion, CIAHZN-J is an excellent genetic stock for the identification of drought-responsive genes and can also be deployed in crop improvement programs for drought tolerance.
干旱和半干旱地区的树种采用多种策略来应对干旱胁迫。印度枣（Ziziphus nummularia (Burm. f.) Wight et Arn.）原产于印度的塔尔沙漠，具有很强的耐旱性。为了确定印度枣最耐旱的生态型，从半干旱地区（戈德拉，年降雨量>750毫米）、干旱地区（比卡内尔，250 - 350毫米）和极度干旱地区（斋沙默尔，<150毫米）各选取一个生态型，同时选取另外两种枣属植物，即毛叶枣（Ziziphus mauritiana Lamk.）和圆叶枣（Ziziphus rotundifolia Lamk.），对有助于耐旱性的参数进行筛选。其中，印度枣（斋沙默尔）（CIAHZN - J）是最耐旱的。CIAHZN - J的耐受特性与膜稳定性增强、根长和根数增加、毛和刺的长度增加、根干重/鲜重比、种子萌发（在-0.5兆帕）、脯氨酸含量（31倍）、过氧化氢酶和糖含量（2至3倍）有关。除了这些特征外，它还表现出达到最高累积干旱胁迫等级所需的时间最长，在较长时间内保持较高的相对含水量，叶片尺寸减小、叶片卷曲以及老叶脱落，并且在干旱胁迫期间茎持续生长。在本研究中，为了确定枣属植物的耐旱性，我们开发了一种基于形态症状的筛选技术。此外，CIAHZN - J对干旱响应的转录组分析揭示了参与糖代谢和运输、脱落酸生物合成、渗透调节、活性氧稳态和维持水势的基因上调。表达谱和半定量逆转录PCR结果进一步与生理和生化机制相关。总之，CIAHZN - J是用于鉴定干旱响应基因的优良遗传资源，也可用于耐旱作物改良计划。
