Miranda Marcela T, Espinoza-Núñez Erick, Silva Simone F, Pereira Luciano, Hayashi Adriana H, Boscariol-Camargo Raquel L, Carvalho Sérgio A, Machado Eduardo C, Ribeiro Rafael V
Agronomic Institute (IAC), Center R&D in Ecophysiology and Biophysics, Laboratory of Plant Physiology "Coaracy M. Franco", P.O. Box 28, Campinas 13012-970, SP, Brazil; University of Campinas (UNICAMP), Department of Plant Biology, Laboratory of Crop Physiology, P.O. Box 6109, Campinas 13083-970, SP, Brazil.
Agronomic Institute (IAC), Center R&D in Ecophysiology and Biophysics, Laboratory of Plant Physiology "Coaracy M. Franco", P.O. Box 28, Campinas 13012-970, SP, Brazil; Universidad Nacional Agraria La Molina (UNALM), Department of Horticulture, La Molina, Lima, Peru.
Plant Sci. 2022 Jun;319:111255. doi: 10.1016/j.plantsci.2022.111255. Epub 2022 Mar 16.
Morpho-physiological strategies to deal with water deficit vary among citrus species and the chemical signaling through ABA and anatomical, hydraulic, and physiological traits were evaluated in saplings of Rangpur lime, Swingle citrumelo and Valencia sweet orange. Trunk and roots of Swingle citrumelo presented lower vessel diameter and higher vessel frequency as compared to the other species. However, relative water content at the turgor loss point (RWC), the osmotic potential at full turgor (Ψ), the osmotic potential at the turgor loss point (Ψ), bulk modulus of elasticity (ε) and the xylem water potential when hydraulic conductivity is reduced by 50% (Ψ) and 88% (Ψ) indicated similar hydraulic traits among citrus species, with Rangpur lime showing the highest hydraulic safety margin. Roots of Rangpur lime and Swingle citrumelo were more water conductive than ones of Valencia sweet orange, which was linked to higher stomatal conductance. Chemical signaling through ABA prevented shoot dehydration in Rangpur lime under water deficit, with this species showing a more conservative stomatal behavior, sensing, and responding rapidly to low soil moisture. Taken together, our results suggest that Rangpur lime - the drought tolerant species - has an improved control of leaf water status due to chemical signaling and effective stomatal regulation for reducing water loss as well as decreased root hydraulic conductivity for saving water resources under limiting conditions.
应对水分亏缺的形态生理策略因柑橘种类而异，我们对兰普莱檬、斯文格枳柚和巴伦西亚甜橙幼树中通过脱落酸的化学信号传导以及解剖学、水力和生理特征进行了评估。与其他种类相比，斯文格枳柚的树干和根系导管直径更小、频率更高。然而，膨压丧失点的相对含水量（RWC）、完全膨压时的渗透势（Ψ）、膨压丧失点的渗透势（Ψ）、弹性模量（ε）以及水力传导率降低50%时的木质部水势（Ψ）和降低88%时的木质部水势（Ψ）表明，柑橘种类间的水力特征相似，兰普莱檬的水力安全边际最高。兰普莱檬和斯文格枳柚的根系比巴伦西亚甜橙的根系更具水分传导性，这与更高的气孔导度有关。在水分亏缺条件下，通过脱落酸的化学信号传导可防止兰普莱檬的地上部分脱水，该种类表现出更保守的气孔行为，能感知并快速响应低土壤湿度。综合来看，我们的结果表明，耐旱种类兰普莱檬由于化学信号传导和有效的气孔调节，在减少水分损失方面对叶片水分状况有更好的控制，并且在有限条件下通过降低根系水力传导率来节约水资源。
