Most of the vineyards around the world are in areas characterized by seasonal drought, where water deficits and high temperatures represent severe constraints on the regular grapevine growth cycle. Although grapevines are well adapted to arid and semi-arid environments, water stress can cause physiological changes, from mild to irreversible. Screening of available Vitis spp. genetic diversity for new rootstock breeding programs has been proposed as a way for which new viticulture challenges may be faced. In 2014, novel genotypes (M-rootstocks) were released from the University of Milan. In this work, the behavior of M1, M3 and M4 in response to decreasing water availabilities (80%, 50% and 20% soil water content, SWC) was investigated at the physiological and gene expression levels, evaluating gas exchange, stem water potential and transcript abundances of key genes related to ABA (abscisic acid) biosynthesis (VvZEP, VvNCED1 and VvNCED2) and signaling (VvPP2C4, VvSnRK2.6 and VvABF2), and comparing them to those of cuttings of nine commercial rootstocks widely used in viticulture. M-rootstocks showed a change at physiological levels in severe water-stressed conditions (20% soil water content, SWC), reducing the stomatal conductance and stem water potential, but maintaining high photosynthetic activity. Water use efficiency was high in water-limiting conditions. The transcriptional changes were observed at 50% SWC, with an increment of transcripts of VvNCED1 and VvNCED2 genes. M-rootstocks showed similar behavior to 1103P and 110R rootstocks, two highly tolerant commercial genotypes. These rootstocks adopted a tolerant strategy to face water-stressed conditions.

中文翻译：

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新型M-砧木（葡萄）基因型如何应对干旱？

世界上大多数葡萄园都处于季节性干旱的地区，缺水和高温严重限制了葡萄的正常生长周期。尽管葡萄藤非常适合干旱和半干旱环境，但水分胁迫会导致生理变化，从轻度到不可逆转。筛选可用的葡萄spp。已经提出了用于新的砧木育种计划的遗传多样性，作为可能面临的新的葡萄栽培挑战的方式。2014年，米兰大学发布了新的基因型（M型砧木）。在这项工作中，在生理和基因表达水平上研究了M1，M3和M4响应于水分利用率降低（80％，50％和20％土壤水分，SWC）的行为，评估了气体交换，茎水势与ABA（脱落酸）生物合成（VvZEP，VvNCED1和VvNCED2）和信号转导（VvPP2C4，VvSnRK2.6和VvABF2）相关的关键基因的转录和转录本丰度），并将其与9种广泛用于葡萄栽培的商业砧木的插条进行比较。在严重的水分胁迫条件下（土壤含水量为20％，SWC），M砧木在生理水平上发生了变化，降低了气孔导度和茎水势，但保持了较高的光合作用活性。在限水条件下，水分利用效率很高。在50％SWC处观察到转录变化，并且VvNCED1和VvNCED2基因的转录本增加。M型砧木表现出与两种高度耐受的商业基因型1103P和110R砧木相似的行为。这些砧木采取了宽容策略来应对缺水条件。