To verify the possible morphological and ultrastructural differences in the Jatropha curcas leaves, in response to high-intensity salt stress, three genotypes were evaluated (CNPAE183, JCAL171, and CNPAE218). In all the genotypes, 750mM NaCl, added to the nutrient solution, was applied to test its salt tolerance. For the analysis, the leaves were collected at three time points: (i) before stress (time 0 hour); (ii) during stress time (time 50 hours); and (iii) in the recovery period (time 914 hours) when the stressed plants recovered and demonstrated measurements of net photosynthetic with values similar to those demonstrated by the control plants. We showed that regardless of the genotype, saline shock caused an increase in the thickness of the mesophyll, and after the removal of NaCl, the thicker mesophyll remained in the JCAL171 and CNPAE218 genotypes, while the values observed in the CNPAE183 genotype were similar to those before stress. Scanning electron microscopy indicated that the stomata of CNPAE183 are smaller and have a stomatal index higher than the values demonstrated in JCAL171 and CNPAE218. Therefore, among the genotypes analyzed, CNPAE183 demonstrates that it could be considered a promising genotype for future studies of genetic improvement that seek elite genotypes tolerant to salinity.

20 Including 4 tables and 3 figures, 1 supplementary figure and 4,503 words 21 22 23 Running Title 24 Leaf morphoanatomy and ultrastructure in Jatropha curcas leaves after salinity shock 25 26 27 2 Salinity shock in Jatropha curcas leaves is more 28 pronounced during recovery than during stress time 29 30 Highlights 31This manuscript present the following highlights: 32The mesophyll thickness contributes to provide a smaller path for the CO 2 to Rubisco 33 J. curcas may reduce mesophyll air spaces as a strategy to mitigate low gas exchange 34Leaves modulate the expansion of stomata differently than other epidermal cells 35Smaller stomata with greater pore aperture are more abundant on the abaxial surface 36 CNPAE183 is a candidate for studies in search of elite genotypes tolerant to salinity 37 38 Abstract 39To verify the possible morphological and ultrastructural differences in the Jatropha curcas 40 leaves, in response to high-intensity salt stress, three genotypes were evaluated (CNPAE183, 41 JCAL171 and CNPAE218). In all the genotypes, 750mM NaCl, added to the nutrient 42 solution, was applied to test its salt tolerance. For the analysis, the leaves were collected at 43 three time points: (i) before stress (time 0 hour); (ii) during stress time (time 50 hours); and 44 (iii) in the recovery period (time 914 hours) when the stressed plants recovered and 45 demonstrated measurements of net photosynthetic with values similar to those demonstrated 46 by the control plants. We showed that regardless of the genotype, saline shock caused an 47 increase in the thickness of the mesophyll, and after the removal of NaCl, the thicker 48 mesophyll remained in the JCAL171 and CNPAE218 genotypes, while the values observed in 49 the CNPAE183 genotype were similar to those before stress. Scanning electron microscopy 50 indicated that the stomata of CNPAE183 are smaller and have a stomatal index higher than 51 the values demonstrated in JCAL171 and CNPAE218. Therefore, among the genotypes 52 analysed, CNPAE183 demonstrates that it could be considered a promising genotype for 53 future studies of genetic improvement that seek elite genotypes tolerant to salinity. 54 Keywords: leaf epidermis; NaCl; physic nut; plant anatomy; stomata, ultrastructural anatomy 55 56 57

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