Long Exposure to Salt Stress in Jatropha curcas Leads to Stronger Damage to the Chloroplast Ultrastructure and Its Functionality Than the Stomatal Function

Abstract

As sessile organisms, plants face a wide range of abiotic stresses, with salinity being a significant condition affecting their growth, development, and productivity, particularly in arid and semi-arid regions. This study focused on understanding how salinity impacts Jatropha curcas, an important oilseed plant for the production of biodiesel. By examining the anatomy and ultrastructure of stomata and chloroplasts, we investigated the effects of prolonged salinity stress on J. curcas. This stress led to changes in the stomatal density, stomatal index, and ostiole aperture, which can cause an imbalance of water conductivity in the xylem. Through transmission electron microscopy, we explored the subcellular organization of J. curcas chloroplasts and their contribution to plant photosynthetic efficiency, providing insights into their role in this process. Notably, increases in salinity resulted in a significant increase in starch granule accumulation, leading to impaired granal and stromal grana lamellae, destroying this ultrastructure. Our findings indicate that the anatomy and ultrastructure of chloroplasts play a crucial role in influencing photosynthetic efficiency. Moreover, impaired hydraulic conductivity due to salinity and a lesser osmotic potential in vessels may cause a reduced source-to-sink relationship, which increases starch accumulation in the chloroplast and influences the ultrastructure of the chloroplast. This study offers a new perspective on the structure and function of chloroplasts in J. curcas, presenting innovative opportunities to develop strategies that enhance the production of biofuel in areas with high soil salinity.

Interannual Variation in Gas Exchange and Leaf Anatomy in Cenostigma pyramidale Is Exacerbated through El Niño and La Niña Climate Events

“…If we compare the average Kp of the rainy year and the dry year, the rainy year showed a 2.4-fold higher Kp compared to the dry year. These data are corroborated by a recent study that showed how hydraulic force is formed in Jatropha curcas plants evaluated over a period of 2 years in an arid climate under irrigation with saline water [27]. Studies with Cyprus species [83] have shown that plants acclimatized in a given environment have a water memory to the point of regulating their Kp according to the need and the time of exposure to stressful conditions.…”

“…In general, gas exchange is intricately governed by a spectrum of factors, encompassing both external environmental conditions and internal physiological aspects within the plant [23]. During episodes of water stress, a typical response involves reduced water transport from the roots to the leaves, which consequently prompts a reduction in stomatal opening for CO 2 uptake [15,[24][25][26][27]. Given that CO 2 serves as the primary substrate for photosynthesis, this diminished uptake often translates into a concurrent decrease in photosynthetic rates.…”

“…Leaf architecture plays a crucial role in facilitating CO 2 exchange within the mesophyll, making the study of plant leaf anatomy and its xylem vessels particularly intriguing. As the plant responds to decreased osmotic potential, it tends to curtail its water flux, impacting all metabolic processes, not limited to photosynthesis alone [27].…”

“…As sessile organisms, plants face a wide range of abiotic stresses, with water stress being a significant condition affecting their growth, development, and productivity, particularly in arid and semiarid regions [27]. Caatinga has a very high plant diversity and rate of endemism but is also a region that is quite degraded because of the unsustainable use of its natural resources; human occupation is followed by abandonment and subsequent natural regeneration of secondary forests [31].…”

Hydrogen Peroxide Alleviates Salt Stress Effects on Gas Exchange, Growth, and Production of Naturally Colored Cotton

“…Salt stress can also alter physiological processes, compromising gas exchange and the production of photoassimilates [7][8][9]. In addition, it can affect the processes of cell division and expansion, consequently inhibiting the growth and therefore the yield of crops [10].…”