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Wild rice (Zizania latifolia Griseb.) is a famous, perennial, emergent vegetable in China. The current work explores the anatomy and histochemistry of roots, stems, and leaves and the permeability of apoplastic barriers of wild rice. The adventitious roots in wild rice have suberized and lignified endodermis and adjacent, thick-walled cortical layers and suberized and lignified hypodermis, composed of a uniseriate sclerenchyma layer (SC) underlying uniseriate exodermis; they also have lysigenous aerenchyma. Stems have a thickened epidermal cuticle, a narrow peripheral mechanical ring (PMR), an outer ring of vascular bundles, and an inner ring of vascular bundles embedded in a multiseriate sclerenchyma ring (SCR). There is evidence of suberin in stem SCR and PMR sclerenchyma cells. Sheathing leaves are characterized by thick cuticles and fibrous bundle sheath extensions. Air spaces in stems and leaves consist of mostly lysigenous aerenchyma and pith cavities in stems. Apoplastic barriers are found in roots and stems.

The perennial selenium (Se) hyperaccumulator Cardamine hupingshanensis (Brassicaceae) thrives in aquatic and subaquatic Se-rich environments along the Wuling Mountains, China. Using bright-field and epifluorescence microscopy, the present study determined the anatomical structures and histochemical features that allow this species to survive in Se-rich aquatic environments. The roots of C. hupingshanensis have an endodermis with Casparian walls, suberin lamellae, and lignified secondary cell walls; the cortex and hypodermal walls have phi (Φ) thickenings; and the mature taproots have a secondary structure with a periderm. The stems possess a lignified sclerenchymal ring and an endodermis, and the pith and cortex walls have polysaccharide-rich collenchyma. Air spaces are present in the intercellular spaces and aerenchyma in the cortex and pith of the roots and shoots. The dense fine roots with lignified Φ thickenings and polysaccharide-rich collenchyma in the shoots may allow C. hupingshanensis to hyperaccumulate Se. Overall, our study elucidated the anatomical features that permit C. hupingshanensis to thrive in Se-rich aquatic environments.

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To examine if the cultivation process has reduced the genetic variation of modern cultivars of the traditional Chinese medicinal plant, Coptis chinensis, the levels and distribution of genetic variation was investigated using ISSR markers. A total of 214 C. chinensis individuals from seven wild and three cultivated populations were included in the study. Seven ISSR primers were used and a total of 91 DNA fragments were scored. The levels of genetic diversity in cultivated populations were similar as those in wild populations (mean PPL = 65.2% versus PPL = 52.4%, mean H = 0.159 versus H = 0.153 and mean I = 0.255 versus I = 0.237), suggesting that cultivation did not seriously influence genetic variation of present-day cultivated populations. Neighbour-joining cluster analysis showed that wild populations and cultivated populations were not separated into two groups. The coefficient of genetic differentiation between a cultivar and its wild progenitor was 0.066 (G(st)), which was in good accordance with the result by amova analysis (10.9% of total genetic variation resided on the two groups), indicating that cultivated populations were not genetically differentiated from wild progenitors. For the seven wild populations, a significant genetic differentiation among populations was found using amova analysis (45.9% of total genetic variation resided among populations). A number of causes, including genetic drift and inbreeding in the small and isolated wild populations, the relative limited gene flow between wild populations (N(m) = 0.590), and high gene flow between cultivars and their wild progenitors (N(m) = 7.116), might have led to the observed genetic profiles of C. chinensis.

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