Vives-Peris Vicente, López-Climent María F, Moliner-Sabater María, Gómez-Cadenas Aurelio, Pérez-Clemente Rosa M
Department of Biology, Biochemistry and Natural Sciences, Universitat Jaume I, Castelló de la Plana, Spain.
Front Plant Sci. 2023 Apr 20;14:1145625. doi: 10.3389/fpls.2023.1145625. eCollection 2023.
Citrus productivity has been decreasing in the last decade in the Mediterranean basin as a consequence of climate change and the high levels of salinity found in the aquifers. Citrus varieties are cultivated grafted onto a rootstock, which has been reported as responsible for plant tolerance to adverse situations. However, other important factors for stress tolerance relying in the scion have been less studied. The aim of this study was to evaluate the effect of the grafted scion on citrus tolerance to salt stress.
Four different citrus rootstock/scion combinations were subjected to salt stress for 30 days, using Carrizo citrange (CC) or (CM) as rootstocks, and Navelina orange (NA) or Oronules mandarin (OR) as scions. CM-OR was the most tolerant combination, whereas CC-NA was the most sensitive one.
Our results support the idea that the rootstock plays an important role in salt stress tolerance, but scion is also crucial. Thus, photosynthesis and transpiration, processes regulated by abscisic acid and jasmonic acid, are determinant of plant performance. These photosynthetic parameters were not affected in plants of the salt-tolerant combination CM-OR, probably due to the lower intoxication with Cl ions, allowing a better performance of the photosynthetic machinery under stress conditions. The different stomatal density of the two citrus scions used in this work (higher in the sensitive NA in comparison to the tolerant OR) also contributes to the different tolerance of the grafted plants to this adverse condition. Additionally, and , genes codifying for Cl tonoplast transporters, were exclusively overexpressed in plants of the salt-tolerant combination CM-OR, suggesting that these transporters involved in Cl compartmentalization could be crucial for salt stress tolerance. It is concluded that to improve citrus tolerance to high salinity, it is important that scions have a versatile photosynthetic system, an adequate stomatal density, and a proper modulation of genes coding for Cl transporters in the tonoplast.
由于气候变化以及含水层中高盐度水平，地中海盆地的柑橘产量在过去十年中一直在下降。柑橘品种是嫁接到砧木上进行种植的，据报道，砧木是植物耐受逆境的原因。然而，关于接穗中其他影响耐逆性的重要因素的研究较少。本研究的目的是评估嫁接接穗对柑橘耐盐胁迫的影响。
以卡里佐枳橙（CC）或（CM）为砧木，以奈维林娜脐橙（NA）或奥罗努尔斯柑桔（OR）为接穗，对四种不同的柑橘砧木/接穗组合进行30天的盐胁迫处理。CM-OR是耐受性最强的组合，而CC-NA是最敏感的组合。
我们的结果支持这样一种观点，即砧木在耐盐胁迫中起重要作用，但接穗也至关重要。因此，由脱落酸和茉莉酸调节的光合作用和蒸腾作用是植物性能的决定因素。这些光合参数在耐盐组合CM-OR的植株中不受影响，这可能是由于Cl离子中毒程度较低，使得光合机制在胁迫条件下能更好地发挥作用。本研究中使用的两种柑橘接穗的气孔密度不同（敏感的NA比耐受的OR更高），这也导致嫁接植株对这种逆境的耐受性不同。此外，编码Cl液泡膜转运蛋白的基因和仅在耐盐组合CM-OR的植株中特异性过表达，这表明这些参与Cl区室化的转运蛋白可能对耐盐胁迫至关重要。得出的结论是，为了提高柑橘对高盐度的耐受性，接穗具有多功能的光合系统、合适的气孔密度以及对液泡膜中Cl转运蛋白编码基因的适当调控非常重要。
